### Please describe the problem.

The man page of  [git-annex findkeys](https://git-annex.branchable.com/git-annex-findkeys/) says: 

> OPTIONS
>
>  *  matching options
>     The git-annex-matching-options(1) can be used to specify which keys to list.

However, this is not true for the options that match file size. Being able to do for example `git-annex findkeys --largerthan 100M`
is important for me as it allows me to track down the files that occupy most of my storage, allowing me to move them to some
archive. However, if I try to call the above command, it does not show me a list of keys matching the criterion, but a help page
as if I have misspelled the option:

>     $ git annex findkeys --largerthan 1
>     Invalid option `--largerthan'
>     
>     Usage: git-annex COMMAND
>       git-annex - manage files with git, without checking their contents in
>     
>     Commonly used commands:
>
>     add             add files to annex
>     [...]

### What steps will reproduce the problem?

[[!format sh """
    echo hi > file
    git annex init
    git annex add file
    git commit -m "Test commit"
    git annex find --largerthan 1   # << this lists "file"
    git annex findkeys --largerthan 1   # << this fails
"""]]

### What version of git-annex are you using? On what operating system?

* git-annex version: 10.20230926-g44a7b4c9734adfda5912dd82c1aa97c615689f57
* Rocky Linux 9.2
* git 2.40.1



### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

I am using it for my research project (data science/predictions in plant breeding) and it allows me to keep track of the
current model iteration and associated results. Thank you for this! 

> [[fixed|done]] --[[Joey]]
